Prior Art
Doped intrinsically conductive polymers have been authoritatively recognized as the "Hottest thing in modern physics". Organic polymers are generally recognized insulators of electrical current flow and are generally complex mixtures of microscopic crystalline and disordered or amorphous elements with no free electrons to carry charges through them. Recent discoveries of polymers having unsaturated carbon to carbon double bonds in the "mers" or repeating groups which are alternative with or "conjugated" in the known polymers, such as polyacetylene, poly(paraphenylene) and poly(p-phenylene sulfide) when treated or "doped" with electron donors or electron acceptor (dopants) have been found to produce conductive polymers.
Prior art conductive polumers have conductivities of the order of about 10.sup.-9 to about 10.sup.3 mhos(S) per cm. Most all known normal prior art polymers are effective insulators. Insulators normally exhibit conductivities of the order of 10.sup.-6 to 10.sup.-15 mhos(S) per cm. Illustratively nylon has a conductivity of the order of about 10.sup.-15 mhos per cm.
The prior art ppears to hve recognized that polymers made up of repeating units or "mers" where each of the units thereof exhibits a conjugated double bond structure, illustrated as (--C.dbd.C--C.dbd.C--C.dbd.C) were those most likely to display semi-conducting properties. Conductivities were found to be evaluated for some compounds in this class somewhere between good insulators and good conductors.
William A. Little of Stanford University proposed in 1965 theoretically that a conjugated polymer (as above) with selected substituents along the linear polymeric conjugated unsaturated backbone should provide a "super conductor". An inorganic polymer, polysulfurnitride, proved to be superconducting at about 0.5 degrees Kelvin.
The number of intrinsically conductive polymers known in the art are representatively very small. Those conductive polymers above have been most investigated and others are known to exist. "Conductive Polymers" (published 1982, Plenum Publishing Corp.) edited by Raymond Seymour provides additional detail of the prior art.
The commercial use of light weight intrinsically conductive polymeric materials to replace conductors and semi-conductors of known quality has, however, been seriously hampered by the inherent instability of the known prior art materials to withstand intimate contact with oxygen and with water, both of which are in ever-present contact with exposed surfaces not otherwise isolated therefrom by protective means.
The inherent instability of the known electrically conducting polymers has been and remains the major deficiency of prior art products. Additionally, the procedure for synthesis of the electrically conducting polymers of the prior art is highly specialized, relatively complicated and costly. Further, the mechanical properties are not particularly attractive for practical application and ultimate utility.
Further, the known conductive polymers are generally found to be insoluble and infusible which is a serious handicap in the formation of these polymers into various commercial complex forms and sizes. In some instances complex forms become difficult, if not impossible, to create.
It is well established in the published state of the art that the conductivity of intrinsically conductive polymers is greatly enhanced through use of dopants which may be either electron donors or electron acceptors. The polymer dopant interaction which leads to the conductivity of an organic polymer is not well understood and is open to a variety of interpretations.
There are two parallel theories or models and opinions to explain the dopant phenomenon. One is the Soliton model and the other is that of conductive islands embedded in a dielectric matrix.
The Solitron model proposed by Su, Schrieffer and Heeger has some experimental support (Physical Review Letter 43, 1532, (1979).
The second model supports the concept that the treatment of the polymer with dopants introduces conductive islands by charge transfer between the polymer backbone and the dopant atoms. Iodine, selected from among the known dopants for experimental use in this developmental work, being an electron acceptor becomes negatively charged by pulling electrons from the backbone and thereby the backbone in turn becomes conductive with positively charged holes.
The Soliton model, specifically in relation to the particular synthetic rubbery homopolymers of interest to this disclosure, does not appear to be clearly applicable. No physical misfit appears formable along the backbone, as could be supported in argument in the case of polyacetylene, the only prior art class of intrinsically conductive polymers described therein.
Prior art made of record in copending application U.S. Ser. No. 481,589, filed Apr. 4, 1983, presently relied upon includes Wingrave, U.S. Pat. No. 4,230,604 which describes treatment of a non-differentiated class of polymers with a conductive salt which is not generally understood to be a dopant treatment. Also of record in the same file are recognized doped prior art polymers which include Heeger, et.al. U.S. Pat. No. 4,204,216 and U.S. Pat. No. 4,222,903 and the prior art made of record in the relevant art therein of record. Also pertinent to the prior art of doped polymers are Pez U.S. Pat. No. 4,269,738.
The known pertinent prior art identified above does not embrace the class of doped homopolymeric rubbery precursor compositions herein disclosed and claimed.
While the polyenes (chain bridged acetylene) polyphenylenes (aromatic ring based polymers) and polyphenylene chalcogenides (sulfur bonded aromatic ring structures) are disclosed in the prior art as dopable polymers using electron acceptor and electron donor dopants, there is no suggestion that the homopolymers disclosed herein are capable of being similarly doped to form a novel class of conductive polymers.